Anesthetic administration sets for intravenous administration are commercially available. A typical set may include two components separated by a substantial length of tubing, for example about 30 inches in length. The forward component of the set may include a T-shaped luer connector structure with a needle adapter at one branch of the T, an injection site at the other branch of the T (to permit connection by the main IV set), and with the base of the T communicating with the 30 inch tubing.
At the other end of the 30 inch tubing, a housing containing a one-way valve is provided, plus a luer for receiving a syringe for anesthetic or other medication to be provided in critical quantities. Accordingly, during an operation, the anesthesiologist can stand behind the surgeon or otherwise out of the way, and yet can administer anesthetic to the patient by forcing the parenteral anesthetic through the one-way valve by means of pressure on the syringe, with the anesthetic passing through the tube to the T-connector, and from there into the patient's bloodstream. The one-way valve prevents backflow due to any hydrostatic pressure head of a connected IV set carrying parenteral solution, or due to the venous pressure of the patient.
One commercially available set of the above type includes a one-way sleeve valve in which the rubber sleeve has a closed end about the inlet orifice so that liquid must pass about the inner surface of the closed end, and then move rearwardly about the orifice until the inner end of the sleeve is passed. Then it turns 180.degree. and flows along the outer surface of the sleeve outwardly on its path to the patient. Such a design is of the general type as shown in Winnard U.S. Pat. No. 3,601,151.
This commercially available design, however, exhibits an excessively high resistance to flow. Also the residual volume of the set is unduly high, so that the surgeon is forced to inject an excess amount of anesthetic, for example, above and beyond that calculated for the patient's need, since an unduly high amount of anesthetic remains caught in the inner volume of the set, and is not provided to the patient.
Furthermore, the closed-end sleeve structure can shift, and can block the outlet orifice if it does shift, rendering the valve possibly inoperative.
Numerous other designs of sleeve valves are also known, but each of them are seen to exhibit certain disadvantages relative to the valve of this invention. For example, the sleeve valve shown in Pennisi U.S. Pat. No. 3,384,113 utilizes a seal ring at the rear of the flexible valve sleeve, to prevent its sliding on the inner tubular support.
This results in a more complex structure, requiring a higher pressure for operation, all other things being equal, since flow out of the rear of the flexible sleeve is completely eliminated.
In Gispen U.S. Pat. No. 2,743,724, a tubular sleeve rests upon a tubular support in an annular recess on the tubular support. Thus, the contact surface between the inner surface of the flexible sleeve and the outer surface of the tubular support is recessed, resulting in a higher pressure resistance, all other things being equal upon operation. Also, upon heavy flow pressures, the flexible sleeve can be blown out of its annular recess, changing the operation of the valve.
Finally, in British Pat. No. 733,890, a tubular sleeve is provided on a tubular inner support in which the free end of the inner support is flared outwardly to serve as a retainer for the tubular sleeve. This also increases the flow resistance of the valve flow, requiring higher pressures since the outer, flared end of the inner support serves as an added flow resistance.
The present invention provides a sleeve valve for a parenteral solution administration set or the like having low residual volume, so that critical medications may be administered in precise quantities and with less waste, while at the same time, the valve provides higher flow rates at lower pressures, in comparison with the structures of the prior art.